1. Field of the Invention
The present invention relates to a data classification method for classifying data about the history of product fabrication and related steps, as well as to a data management method, a data base and a data storage medium based on that data classification method.
2. Description of the Related Art
Conventionally, data about the history of products and specifically about their fabrication processes are given meaningful names that illustratively represent combinations of such processes. Where the number of fabrication processes is large enough, the combinations resulting from even a minor change for fabrication improvement can be extensive. The combinations of such fabrication processes can be so numerous that it may be difficult to namexe2x80x94hence classify distinctlyxe2x80x94all the processes involved. This in turn makes it impossible to know retroactively the historical data of the processes involved.
It is therefore an object of the present invention to provide a data classification method for allowing complex and varying fabrication processes having numerous conditional alternatives used in factories and the like to be precisely represented and distinctly classified by historical data about fabrication.
Typically, throughout the fabrication processes of semiconductor devices, there are occasions requiring the classification of impurity distributions, electrical characteristics, cross-sectional views and other measurements of fabricated wafers, as well as of the wafers themselves. In such cases, the present invention provides a method for readily knowing the history of specific wafers to which specific data belong as well as the processes of fabrication that the wafers have undergone. Besides classifying historical data on the fabrication of semiconductors, the inventive method may be used advantageously to classify the history of any goods and products fabricated or prepared by a plurality of processes or steps.
According to one aspect of the present invention, a data classification method comprises data fields for accommodating historical data constituted by combinations of a first kind of symbols, and each of the first kind of symbols represents each process making up a history.
According to another aspect of the present invention, a data classification method comprises data fields for accommodating a second kind of symbols corresponding to historical data. Each of the historical data is constituted by a combination of a first kind of symbols, and each of the first kind of symbols represents each process making up a history.
In the data classification method, the history may be associated with fabrication of products, and the first kind of symbols representing the processes denote types of processes constituting the fabrication.
In the data classification method, the first kind of symbols denoting the types of the processes constituting the fabrication may be delimited by delimiter symbols.
In the data classification method, the types of the processes constituting the fabrication may be each represented by either one or a fixed number of characters.
In the data classification method, the types of the processes constituting the fabrication may be each represented by a varying number of characters.
According to another aspect of the present invention, a data management method manages data according to any one of the data classification methods as described above.
According to another aspect of the present invention, a database comprises historical data classified according to any one of the data classification methods as described above.
According to another aspect of the present invention, a data storage medium stores historical data classified according to any one of the data classification methods as described above.
Briefly, the present invention comprises, in one embodiment, a computer implemented data classification and retrieval method for classifying, organizing and retrieving fabrication process data for a product by computer, comprising the steps of: representing each type of process in a plurality of processes for fabricating a product by a first kind of symbol; forming a first record file that includes a fabrication process representation by combining the first kinds of symbols in a chronological process sequence into a first character string; associating information with the record file for a plurality of the different first kinds of symbols in the character string; associating each character string with measurement data; and selecting and retrieving a plurality of record files that have the same character string.
In a further aspect of the present invention, the method comprises the steps of: representing a particular one of the character strings by a second kind of symbol; and forming a second record file by combining individual symbols in a chronological process sequence, including a symbol of the second kind, to form a second character string.
In a yet further aspect of the present invention, a memory is provided for storing data for access by a computer program executed on a data processing system, comprising: a data structure stored in the memory, the data structure including information resident in a database used by the computer program and including: a plurality of different process data objects of a first kind, each different data object of a first kind representing a different fabrication process for a product; a plurality of different first character string data objects, each different first character string data object representing a first chronological fabrication process and being formed by combining a plurality of the process data objects of a first kind in a chronological process sequence; at least one process data object of a second kind for representing one of the plurality of first character string data objects; and at least one second character string data object representing a second chronological fabrication process and being formed by combining individual process data objects, including at least one process data object of the second kind.
Other and further objects, features and advantages of the invention will appear more fully from the following description.